In a tweet Tuesday morning, the 2016 Democratic presidential nominee pointed to a recent spike in vandalism of Jewish graves and bomb threats leveled against Jewish community centers and urged "everyone," "starting with" Trump, to speak out.

Trump has faced criticism for failing to vocally denounce anti-Semitism. He did acknowledge the issue, however, later Tuesday morning during an interview with MSNBC.

"Anti-Semitism is horrible, and it's going to stop, and it has to stop," Trump said.

It was unclear whether the issue was brought up Tuesday in response to Clinton's tweet, but Trump has been more reluctant to speak out in the past. Asked at a press conference last week what he would do to address anti-Semitic crimes, he chastised the reporter who asked the question, telling him to "sit down" and saying the question was "not a simple question, not a fair question."

"I am the least anti-Semitic person that you've ever seen in your entire life. No. 2, racism, the least racist person," Trump said, before summarizing his Electoral College victory in November.

"In fact we did very well relative to other people running as a Republican. Quiet, quiet, quiet," he said, again addressing the reporter, who had made it clear he was not accusing Trump of being anti-Semitic. "So he lied about — he was going to get up and ask a very straight simple question. So you know, welcome to the world of the media. But let me just tell you something, that I hate the charge. I find it repulsive. I hate even the question."

Critics have blasted White House chief strategist Steve Bannon's former stewardship of Breitbart, a far-right website that has attracted an anti-Semitic readership. And last month, the White House defended an official Holocaust remembrance press release that did not specifically mentions Jews.